In many chemical supply systems, the amount of chemicals disbursed from the system must be strictly controlled. Supply of chemicals is normally controlled by valves. Often, a control system operates an actuator that changes or maintains the valve position. For example, the medical field frequently uses control systems, which operate actuators and valves, to control the supply of various drugs. This chemical supply equipment must frequently be placed in aggressive environments. As a result, the supply of chemicals may be inhibited and acquisition of data related to the chemical supply may be inaccurate. In addition, the chemical supply system could be subject to corrosion or other damage in these aggressive environments.
Another source of problems with present chemical sensor systems is the wiring itself. For example, noise may be introduced into the supply system due to noise induction in the wiring between the chemical supply and the control circuitry. In addition, the use of wiring tends to result in no galvanic separation, which may cause ground loops or isolation problems.
Another problem with typical chemical supply systems results when the supply of chemicals is controlled by battery. Batteries result in large and costly systems. Furthermore, the chemical supply systems must be frequently accessed to maintain operation by changing the battery.
Furthermore, another problem results when attempting to build a chemical supply system in which control circuitry must be multiplexed between multiple chemical supplies. Such systems require control circuitry to be physically moved between different chemical supplies to effectively multiplex the equipment. This results in an inconvenience to the user of the chemical supply system. In addition, other problems may result due to the need to constantly detach and reattach control equipment when multiplexing chemical supplies.